Various known conveyors are employed in underground mining operations. Such conveyors are normally of a type comprising an endless belt in which the belt moves in one direction when it is carrying mined material with the belt running in the opposite direction when it changes from the return path to the load bearing path. In order to form a belt path and to support both the weight of the belt and the weight of the payload an elaborate assembly of load bearing and guide rollers are required. The rollers are typically supported on frames that are located at discrete intervals and anchored to the underground tunnels. The frames may rest on the mining floor or be suspended from the roof by chains or from a wall by brackets to achieve the required stability.
As underground mining operations progress it is often necessary either to lengthen or shorten a conveyor. One example where this is required is in a longwall mining operation. There are two basic forms of longwall mining operation, namely advancing face and retreating face systems. An advancing face, as the term suggests, advances together with its roadways deeper into the area of material being mined. A retreating face on the other hand starts at the furthest point required in the area of material to be extracted and retreats towards the entrance.
Although loop take-up arrangements are known for facilitating lengthening and shortening of belts associated with such conveyors, the addition or removal of frames necessary to support the rollers associated with the conveyor system is a time consuming process. This process is also hazardous as the frames must be carried up and down the tunnels through which the conveyor passes, often whilst the conveyor is in operation. Also, erecting and collapsing roller support frames is time consuming and results in down time for and damage to mining and tunnelling projects. A further drawback of existing conveyors is the fact that replacement of worn or failed components is a heavy and awkward task. This is particularly true if the conveyor is loaded with mined material as the combined weight of the belting and material can be significant. The difficultly is exacerbated by the confined areas in which installation, recovery and maintenance is to be carried out.
Various safety standards are prescribed for conveyor systems. Often, however, mining entities are guilty of non-compliance with those standards for failure to provide sufficient guarding of conveyor systems in underground mines. The reason for this is that guarding of conveyor systems would typically require punched steel sheeting or welded mesh panels to be installed. Given the above ergonomic constraints, carrying, installation and recovering panels of mesh only adds to already existing handling difficulties.